With the development of high strength, low porosity, economical non-metallic materials in recent years such as polycarbonate, vinyl, nylon, acetal and other synthetic polymer materials, it has become feasible and economically desirable to produce and market pipe sections and other pipeline elements, such as water meters, valves etc., made of such materials. Normally, such pipeline elements are connected into pipeline systems by means of threaded connections, and it is customary, for example, in the water meter art to provide the inlet and outlet sections of water meters with externally threaded male connecting sections which are received into internally threaded female coupling nuts on the section of pipe to which the meter is to be coupled. However, when the meter body is made of plastic, it has been found that when such threads are formed directly on the inlet and outlet sections of the meter body, because the plastic material is relatively soft, and the female pipe coupling to which it is to be connected is usually metal and may be slightly misaligned with the axis of the spud when the meter and the female coupling on the pipe section to which it is to be joined are connected together with sufficient locking force to insure a fluid tight seal, the threads on the meter spud frequently become damaged or cross threaded making it impossible to obtain a fluid tight seal. If the threads are formed directly on the spuds, damaged threads require that the entire meter be discarded. Various solutions to this problem have been proposed, one of which is to provide a replaceable threaded sleeve such as disclosed in the U.S. Pat. No. 4,126,338 to Coel et al. The arrangement shown in that patent employs a resilient threaded integral sleeve which is snap-fitted over the end of the pipe section or spud extending from the body of the meter. The sleeve is held in positon by means of protuberances which extend from the inside of the sleeve and are received into recesses located on the exterior surface of the meter spud. In such an arrangement if the threads on the sleeve become damaged, the sleeve is removed and replaced with a new, undamaged sleeve. It will be appreciated, however, that since that arrangement employs an interference or snap fit between the sleeve which is comprised of an integral cylinder, and the spud of the meter, mounting of the sleeve and its removal may be somewhat difficult and could cause damage to the pipe section or meter spud. Also, it should be noted that replacement of the sleeve requires removal of the meter from the line whereas with the instant invention the collar or sleeve may be replaced without removing the meter from the line.
Applicants propose an externally threaded sleeve comprised of two identical semi-circular members mounted on the end of the pipe or meter spud. Pipe couplings employing semi-circular externally threaded members are shown in the prior art of which the U.S. patents to Driscoll U.S. Pat. No. 296,394; Westinghouse et al. U.S. Pat. No. 1,586,725; Peterson U.S. Pat. No. 2,569,333 and French Pat. No. 1,197,185 are typical. However, none of the prior art shows a coupling employing easily removable identical semi-circular externally threaded members with piloting means to insure proper orientation of the semi-circular members when assembled on the pipe end and which may be snap fitted on the end of the pipe to insure its retention thereon.